Question 979447
<pre>
{{{x^2-(a+3b)x+3ab=0}}}

Distribute to remove the parentheses:

{{{x^2-ax-3bx+3ab=0}}}

Factor x out of the first two terms

{{{x(x-a)-3bx+3ab=0}}}

Factor -3b out of the last two tems:

{{{x(x-a)-3b(x-a)=0}}}

Factor (x-a) out of both terms:

{{{(x-a)(x-3b)=0}}}

Use the zero-factor property:

{{{x-a=0}}}     {{{x-3b=0}}}
  {{{x=a}}}       {{{x=3b}}}

Edwin</pre>